Segregating foreign objects from a stream of tobacoo

ABSTRACT

A method and apparatus for segregating foreign objects out of a tobacco stream. The tobacco stream is fed into a conveyor and conveyed past a foreign-object detecting device which detects a foreign object in the tobacco stream. A diverter is arranged in the conveyor to divert the tobacco stream downstream of the detector. A mechanical valve arrangement in the region of the diverter transfers a portion of the tobacco stream containing the detected foreign object out of the tobacco stream such that the tobacco stream containing the foreign object is not diverted and the remainder of the stream is diverted.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of German Application No. 10 2004 048 744.8, filed on Oct. 5, 2004, the subject matter of which is incorporated herein by reference. The foregoing application together with each U.S. and foreign patent and patent application mentioned below are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to a method for segregating foreign objects from a stream of tobacco, wherein the tobacco stream is conveyed past a foreign-object detecting device and wherein foreign objects in the tobacco stream are detected by the foreign-object detecting device. The invention furthermore relates to an apparatus for segregating foreign objects from a tobacco stream, the apparatus comprising a feeding conveyor for the tobacco stream and a foreign-object detecting device inside the feeding conveyor for detecting the foreign objects in the tobacco stream.

An apparatus for segregating foreign objects from a tobacco stream is known, for example, from U.S. Pat. No. 6,332,543, commonly owned by the Assignee of the present application. The known apparatus is used to convey a stream of tobacco with the aid of conveyors, in particular a trough conveyor and conveying belts, to the region or range of an optical foreign-object detecting device. Foreign objects in the tobacco stream which are detected by the foreign-object detecting device are then segregated from the tobacco stream by compressed air blown transverse to the conveying direction.

European Patent document EP-B-0 479 549 discloses an apparatus for screening de-ribbed tobacco leaves.

SUMMARY OF THE INVENTION

It is an object of the present invention to improve the segregation of foreign objects from a tobacco stream.

The above and other objects are accomplished according to one embodiment of the invention in which there is provided a method for segregating foreign objects out of a tobacco stream, comprising: conveying the tobacco stream past a foreign-object detecting device; detecting a foreign object in the tobacco stream with the foreign-object detecting device; diverting the tobacco stream; and transferring a portion of the tobacco stream containing the detected foreign object out of the tobacco stream in a region of the diverter such that the tobacco stream containing the foreign object is not diverted and the remainder of the stream is diverted. Within the scope of the invention, the terms divert and diverter comprise the meaning of the terms deflect and deflector.

According to one exemplary embodiment, the transferring step includes using a mechanical valve arrangement to transfer out the portion of the tobacco stream containing the detected foreign object.

The invention is based on the idea of purposely transferring undesirable or interfering foreign objects out of a stream of tobacco while, simultaneously, using a diverter to divert the portion of the tobacco stream, free of foreign objects, to a following conveying section for further transport. The tobacco-stream portions loaded with undesirable foreign objects are selectively segregated from the tobacco stream without being diverted, meaning they continue to move substantially in a straight line as a result of the centrifugal force and/or the translational movement, whereas the portions free of foreign objects are diverted.

For the purpose of this invention, the term tobacco in particular refers to cut tobacco, tobacco leaves, tobacco strips, leaf tobacco, as well as cloves. Foreign objects in the tobacco stream are detected on the basis of at least one detectable characteristic, such as brightness, color, humidity, or dielectric property. The method according to the invention on the whole permits a high rate of segregating out foreign objects from a tobacco stream while, simultaneously, resulting in a high quality tobacco good which is further processed in different machines.

According to one advantageous modification of the invention, the tobacco stream and/or the tobacco stream portions loaded with foreign objects are at least in part transferred or guided out of the tobacco stream by several valve elements of a valve arrangement.

If the valve elements are activated independent of each other and/or in dependence on the presence of foreign objects in the tobacco stream and/or the tobacco stream portions, then only those portions of a tobacco stream in which foreign objects have been detected are purposely segregated out or removed from the tobacco stream.

To reliably segregate foreign objects from the tobacco stream, using the valve arrangement, the tobacco stream and/or the tobacco-stream portions loaded with foreign objects are at least partially transferred or guided out of a feeding conveyor downstream of the foreign-object detecting device, based on the results obtained with the foreign-object detecting device.

According to the invention, the tobacco stream that is free of foreign objects can thus be diverted and the foreign objects detected in the tobacco stream can be segregated out from the tobacco stream by the valve arrangement including the individual valve elements. In particular, predetermined segments and/or portions of the tobacco stream in which foreign objects have been detected can be transferred out while tobacco-stream portions without foreign objects are diverted and are conveyed further in the feeding conveyor. In this way, the tobacco-stream portions loaded with foreign objects are selectively removed from the feeding conveyor, so that the feeding conveyor section following the diverter essentially only continues to convey the substance-free portions of the tobacco stream.

Accordingly, only the substance-free portions of the tobacco stream are diverted in the region of the diverter.

An extremely effective conveying of the tobacco stream is furthermore achieved if the fed-in tobacco is conveyed pneumatically with compressed air and/or vacuum air, at least in the region of the foreign-object detecting device. The speed of the tobacco stream preferably ranges from about 2 m/s to about 30 m/s and in particular from about 17 m/s to about 25 m/s.

Substantially constant flow conditions are achieved, in particular, if the conveying speed for feeding the tobacco stream is the same or nearly the same, at least in the region of the foreign-object detecting device, as the conveying speed for transferring out the tobacco stream.

According to another aspect of the invention there is provided an apparatus for segregating foreign objects out of a tobacco stream, comprising: a feeding conveyor for conveying the tobacco stream in a conveying direction; a foreign-object detecting device inside the feeding conveyor for detecting foreign objects in the tobacco stream; a diverter to divert the tobacco stream; and a mechanically operating valve arrangement arranged downstream of the foreign-object detecting device, and in the region of the diverter, preferentially transverse to the conveying direction of the tobacco stream, wherein the valve arrangement is operative to transfer out a portion of the tobacco stream containing a foreign object from the tobacco stream in the region of the diverter.

Accordingly, in the region of the diverter, the tobacco stream and/or the tobacco-stream portions loaded with foreign objects can at least in part be transferred or guided out of the tobacco stream with the aid of the valve arrangement, without being diverted. The tobacco stream and/or the tobacco-stream portions free of foreign objects are diverted while the tobacco stream and/or the tobacco-stream portions loaded with foreign objects are segregated out of the fed-in tobacco stream as a result of the centrifugal force and/or the translational movement of the particles.

One advantageous embodiment of the apparatus is provided with several valve elements to selectively segregate out foreign objects and/or remove portions of the tobacco stream loaded with foreign objects by purposely transferring and/or guiding out of the production or conveying process the tobacco stream and/or the tobacco-stream portions containing foreign objects.

In one exemplary embodiment the valve elements can be operated independent of each other and/or in dependence on the presence of foreign objects in the tobacco stream and/or the tobacco-stream portions. A selective removal and/or separating out of foreign objects from the tobacco stream can thus be achieved.

In another embodiment of the invention, the valve elements are operated by separate drives.

In a further exemplary embodiment, the valve arrangement includes several valve elements arranged side-by-side in a row.

The valve arrangement including several valve elements is thus operative to alternately transfer out at least in part a fed-in tobacco stream loaded with foreign objects and/or for diverting the tobacco-stream without foreign objects inside the feeding conveyor.

The valve elements according to one exemplary embodiment are designed in the form of flaps.

According to another exemplary embodiment, at least the tobacco stream and/or the tobacco-stream portions can be guided out of the feeding conveyor, at least in part on the basis of the results obtained with the foreign-object detecting device. A diverter for the tobacco stream is provided downstream of the foreign-object detecting device, so that the tobacco stream and/or the tobacco-stream portions containing foreign objects are not diverted because of the opening of the valve elements and are ejected and/or discharged from the feeding conveyor as a result of the translational movement or the centrifugal force of the tobacco particles, as well as the foreign objects and, if applicable, are transported off.

In a further exemplary embodiment, a compressed air source and/or a vacuum source are provided for pneumatically conveying the tobacco stream inside the feeding conveyor.

Favorable flow conditions for segregating foreign objects out of the tobacco stream are achieved once the conveying speed of the tobacco stream inside the feeding conveyor essentially corresponds to the conveying speed of the tobacco stream in the feeding conveyor section following the diverter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the invention will be further understood from the following detailed description of the preferred embodiments with reference to the accompanying drawings to which reference is made for all details not expressly mentioned in the text.

FIG. 1 is a perspective, cross-sectional view through a device according to the invention for segregating foreign objects from a tobacco stream.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 represents a schematic view of an apparatus for segregating foreign objects out of a pneumatically conveyed tobacco stream. Following the feeding of tobacco into a separator, via an air lock that is not shown herein, an excess pressure is generated by means of a connected feeding conveyor 60 and a compressed air source which is not shown herein, such that a tobacco stream is generated in the feeding conveyor 60. On the feed-in side, the tobacco stream is conveyed in a straight line inside the feeding conveyor 60 and is transported past a foreign-object detecting device 15. Once it has passed the foreign-object detecting device 15, the tobacco stream continues to be conveyed with vacuum air inside a straight-line conveying section of the feeding conveyor 60. The straight-line section of the feeding conveyor 60 is followed by a curved section 65, allowing the tobacco stream to be conveyed further following the curved section 65.

In the horizontal section of the feeding conveyor 60, the tobacco stream which is indicated with fine dashes is inspected across its total width with the foreign-object detecting device 15, transverse to the conveying direction of the tobacco stream, to determine whether the tobacco stream contains and carries along foreign objects. A foreign object 51 in the tobacco stream can be detected by using physical methods, for example optical methods (laser, CCD camera).

The tobacco stream is then conveyed further toward the curved conveying section 65. The curved conveying section 65 functions to divert the horizontally conveyed tobacco stream, such that the stream continues to be conveyed in the adjacent conveying section. The curved conveying section 65 is provided on the outside with a valve arrangement 70, which is incorporated into the curved conveying section 65. The valve arrangement 70 comprises several side-by-side arranged valve flaps 72.1, 72.2, 72.3, and 72.4.

FIG. 1 schematically shows that the valve flap 72.1 is connected to an actuator 74.1 which functions as a drive. The actuator 74.1, which is connected to the foreign-object detecting device 15, controls the valve flap 72.1 in dependence on the measuring results obtained with the foreign-object detecting device 15. For reasons of clarity, additional actuators for the valve flaps 72.2 to 72.4 are not illustrated.

FIG. 1 furthermore shows a foreign object 51 at the edge of the tobacco stream. Following its detection, the foreign object 51 together with the surrounding tobacco particles continues to be conveyed toward the curved conveying section 65. The movement time required for the foreign object 51 to reach the valve arrangement 70 and/or the curved conveying section 65 is determined on the basis of the constant flow conditions in the feeding conveyor 60. In dependence on the time determined for the movement, the outer valve flap 72.4 is opened, so that the foreign object 51 continues to move in a straight line as a result of the centrifugal force and is not diverted into the curved conveying section 65. The opened valve flap 72.4 is then closed again to allow the tobacco stream in this portion, which is free of foreign objects, to flow into the perpendicular conveying section.

The valve flaps 72.1 to 72.4 are activated based on the local resolution for detecting the foreign object particles in the tobacco stream, so that the share of the fed-in tobacco stream and/or a predetermined tobacco stream portion containing the detected foreign objects can be transferred out. The remaining portions of the tobacco stream, which are free of foreign objects, are diverted and conveyed further because the valve flaps are in the closed position. The valve flaps 72.1 to 72.4 are operated in dependence on the measuring results from the foreign-object detecting device 15. For this, the valve flaps 72.1 to 72.4 are respectively provided with separate drives, wherein pneumatic drives as well as electromagnetic drives are particularly suitable for use.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims. 

1. A method for segregating foreign objects out of a tobacco stream, comprising: conveying the tobacco stream past a foreign-object detecting device; detecting a foreign object in the tobacco stream with the foreign-object detecting device; diverting the tobacco stream; and transferring a portion of the tobacco stream containing the detected foreign object out of the tobacco stream in a region of the diverter such that the tobacco stream containing the foreign object is not diverted and the remainder of the stream is diverted.
 2. The method according to claim 1, wherein the transferring step includes using a mechanical valve arrangement to transfer out the portion of the tobacco stream containing the detected foreign object
 3. The method according to claim 2, wherein the using step includes using a mechanical valve arrangement including several valve elements.
 4. The method according to claim 3, wherein the using step includes actuating the valve elements separately in dependence on the presence of a foreign object in a portion of the tobacco stream.
 5. The method according to claim 1, wherein the conveying step includes conveying the tobacco stream in a feeding conveyor; and the transferring step includes guiding the portion of the tobacco stream containing the foreign at least partially out of the feeding conveyor downstream of the foreign-object detecting device in response to results of the foreign-object detecting device.
 6. The method according to claim 5, wherein the diverting step includes diverting the portions of the tobacco stream which are free of foreign objects in the region of the diverter.
 7. The method according to claim 1, wherein the conveying step includes pneumatically conveying the fed-in tobacco stream at least in the region of the foreign-object detecting device.
 8. An apparatus for segregating foreign objects out of a tobacco stream, comprising: a feeding conveyor for conveying the tobacco stream in a conveying direction; a foreign-object detecting device inside the feeding conveyor for detecting foreign objects in the tobacco stream; a diverter to divert the tobacco stream; and a mechanically operating valve arrangement arranged downstream of the foreign-object detecting device and in the region of the diverter, wherein the valve arrangement is operative to transfer out a portion of the tobacco stream containing a foreign object from the tobacco stream in the region of the diverter.
 9. The apparatus according to claim 8, wherein the mechanically operating valve arrangement is arranged transverse to the conveying direction of the tobacco stream.
 10. The apparatus according to claim 8, wherein the valve arrangement comprises several valve elements.
 11. The apparatus according to claim 10, wherein the valve elements are actuatable separately in dependence on the presence of a foreign object in a portion of the tobacco stream.
 12. The apparatus according to claim 10, further including a plurality of drives each operating a respective one of the separate valve elements.
 13. The apparatus according to claim 10, wherein the several valve elements are arranged side-by-side in a row.
 14. The apparatus according to claim 10, wherein the valve elements are comprised of flaps.
 15. The apparatus according to claim 8, wherein the mechanical valve arrangement is responsive to the foreign-object detector to transfer the portion of the tobacco out of the feeding conveyor.
 16. The apparatus according to claim 8, further including a compressed air source or a vacuum source coupled to the feeding conveyor to pneumatically convey the tobacco stream inside the feeding conveyor. 